Heat shields of this type are used wherever temperature-sensitive assemblies, components or connection lines have to be protected in such a way that heat radiation cannot impact directly on them. This is especially the case with motor vehicles where hot parts of the drive assembly are arranged in direct spatial proximity to other temperature-sensitive assemblies.
The ever-improving utilisation of the engine compartments of motor vehicles leads to heat-sensitive components having to be arranged very close to very hot components, such as, for example, the exhaust system, the combustion engine or the heat exchangers. There is therefore a great need for heat shields particularly in the automobile industry.
From DE 38 34 054 C2 is known a heat shield, in which, in order to protect from heat radiation, at least two flat materials are used which are connected to one another on at least two edge regions turned away from one another. The flat materials mentioned are connected to one another in such a way that a gap is formed between them. Moreover, with this known heat shield it is important that the flat material facing the source of the heat radiation is so oriented in its expansion characteristic by pre-determined profiling or beading or corresponding choice of material that it expands towards the heat source. Through corresponding configuration, adaptation to the heat load arising should be made possible, since with higher temperatures the spacing of the two flat materials used, which preferably consist of sheet metal, is increased and an enlarged air gap is produced which naturally improves the insulation effect.
This heat shield can be further improved in relation to its insulating effect if a heat insulation layer is applied in addition to the inner surfaces of the flat materials proposed there. Specially suitable for this purpose are particularly organic or inorganic fibre materials, but also metallic woven fabrics, knitted fabrics or expanded metals (grids). These furthermore improve the sound insulation which is also obtained through these heat shields.
This heat shield has, however, the disadvantage that it is not possible for every conceivable contour of the heat shield to be configured, in order to achieve the desired effect for adaptation to the different temperatures. Moreover, the insulating effect is limited if only an air gap is used without additional heat-insulating materials.
However, where heat-insulating materials are used as the heat insulation layer, which are applied to the external plates of the heat shield, increased production and cost outlay must be reckoned with. Alternatively, the heat insulation layer may be inserted between the two external plates of a heat shield. For this purpose, however, the material to be inserted as the heat insulation layer has to be bonded by means of a binding agent. Binding agents of this kind generally have organic components which cause problems at high temperatures. In particular, the organic binding agents used for this purpose are both ecologically and toxicologically unsafe, since at the high temperatures occurring they give off gases or carry out chemical reactions.
From PCT/DE98/00065, therefore, is known a method for manufacturing a heat shield in which an insulating material in powder and/or flake form and free of binding agent is applied to one of the two flat materials formed as plates, and then compacted at least in regions through the effect of pressure. Then the second flat material, also configured as a plate, is laid on the insulating material and brought, for instance by folding, into a positive or non-positive connection with the lower flat material. What is advantageous about this method is that it is possible to do without the use of an ecologically or toxicologically unsafe binding agent. What is disadvantageous, however, is that the loose, pourable insulating material has to be applied exactly to the lower plate in the desired distribution. To this end it is necessary to apply the pourable material exactly to a component of the heat shield to be manufactured. This method of production is therefore expensive and cost-intensive.
Proceeding from the above, it is therefore the object of the present invention to quote a method and a heat shield manufactured with the method, which may be carried out or respectively manufactured simply and with low costs. In particular, the heat shield is intended to be safe from every toxicological and ecological point of view.